Method for preparing silicon by using gas-phase electroreduction

Abstract

The present invention relates to a method for preparing silicon by using gas-phase electroreduction and, more specifically, to a method in which a silicon-based compound is gas-phase supplied, without a liquid medium, onto the surface of a base metal having a potential applied thereto, and thus silicon is reduced and applied onto the surface of the base metal.

The invention claimed is: 
     
       1. A silicon preparation method using gas-phase electroreduction, the silicon preparation method comprising:
 inserting a base material including a carbon-based negative electrode active material comprising voids into a reactor; 
 applying an electrical potential to a surface of the base material located in the reactor; 
 gas-phase supplying a silicon-based compound to the base material having the electric potential applied thereto so that electrons are supplied to the silicon-based compound on the surface of the base material in the reactor; and 
 forming a silicon coating layer having a thickness in a range of 5 to 100 μm and comprising a plurality of spherical nanoparticles having a diameter in a range of 5 to 100 μm in the form of films or one or more islands on the surface of the base material by using the electrons to reduce the gas-phase silicon-based compound on the surface of the base material and to electrically bond the spherical nanoparticles with the carbon-based material at an interface therebetween to prevent irreversible capacity loss; 
 wherein the silicon coating layer is formed in a state in which the films and the islands filling the voids are mixed with each other to control distribution of the plurality of nanoparticles so as to be uniform and to achieve attachment to the base material without electrical resistance. 
 
     
     
       2. The silicon preparation method according to  claim 1 , wherein the silicon-based compound is silicon tetrachloride (SiCl 4 ), hexachlorodisilane (Si 2 Cl 6 ), dichlorosilane (SiH 2 Cl 2 ), methylsilane (CH 3 SiH 3 ), tetrakis(trichlorosilyl)silane, or silicon tetrafluoride (SiF 4 ). 
     
     
       3. The silicon preparation method according to  claim 1 , wherein the base material is graphite, copper, lithium, aluminum, stainless steel, or a battery material of NMC/NCA. 
     
     
       4. A lithium-ion/metal battery comprising:
 a positive electrode; a negative electrode; and an electrolyte, 
 wherein the negative electrode comprises the silicon coating layer prepared by the method according to  claim 1 . 
 
     
     
       5. A lithium-ion/metal battery comprising:
 a positive electrode; a negative electrode; and an electrolyte, 
 wherein the negative electrode comprises the silicon coating layer prepared by the method according to  claim 2 . 
 
     
     
       6. A lithium-ion/metal battery comprising:
 a positive electrode; 
 a negative electrode; and 
 an electrolyte, 
 wherein the negative electrode comprises the silicon coating layer prepared by the method according to  claim 3 .